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      <title>在分布式系统中如何避免或解决单点故障问题？ - 交互式测验</title>
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    <body>
      <div class="main-wrapper">
          <div class="quiz-container">
            <div class="quiz-header">
              <h1>在分布式系统中如何避免或解决单点故障问题？ - 交互式测验</h1>
              <p>检验你对文档内容的理解程度</p>
            </div>
            <div id="quiz-content">
                <div class="quiz-body">
                    <div class="progress-bar">
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  {
    "question": "文档中讨论的“冗余设计”、“负载均衡”和“去中心化设计”等多种技术策略，其共同的核心目标是解决分布式系统中的哪一个根本性问题？",
    "options": [
      "网络延迟问题",
      "数据不一致性问题",
      "开发和维护成本过高的问题",
      "单点故障 (SPOF) 问题"
    ],
    "correctAnswerIndex": 3,
    "explanation": "文档开篇就定义了单点故障（SPOF），即系统中某个组件的故障导致整个系统不可用。后续讨论的所有策略，如冗余、负载均衡等，都是为了提高系统的可靠性和容错能力，从而避免或解决单点故障。",
    "source": "文档开篇第一段及全文主旨",
    "hint": "文档的第一句话就定义了本文要解决的核心问题。"
  },
  {
    "question": "根据文档，「负载均衡」策略虽然能提高可用性，但其自身也存在一个显著的潜在风险。这个风险是什么？",
    "options": [
      "会显著增加网络延迟，影响用户体验",
      "负载均衡器本身可能成为新的单点故障",
      "只能通过昂贵的专用硬件实现，成本高昂",
      "会使后端的服务实例难以进行故障转移"
    ],
    "correctAnswerIndex": 1,
    "explanation": "文档明确指出，虽然负载均衡器通过分发流量来避免后端服务的单点故障，但如果负载均衡器自身出现故障且没有冗余备份，它就会成为整个系统流量的入口瓶颈，从而形成一个新的单点故障。",
    "source": "文档中「2. 负载均衡」部分的「缺点」",
    "hint": "思考一下，如果那个负责分发所有请求的“交通警察”自己倒下了，会发生什么？"
  },
  {
    "question": "在「分布式存储」一节中，提到了哪两种核心策略来避免单个存储节点故障导致数据问题？",
    "options": [
      "数据复制与数据分片",
      "数据索引与数据缓存",
      "数据压缩与数据加密",
      "数据流处理与数据虚拟化"
    ],
    "correctAnswerIndex": 0,
    "explanation": "文档中明确列出了分布式存储的两种策略：数据复制（在多个节点上存储副本以保证高可用性）和数据分片（将数据拆分存储在不同节点上以提高可扩展性和容错能力）。",
    "source": "文档中「3. 分布式存储」部分的「策略」",
    "hint": "为了保护数据，一种方法是“多准备几份”，另一种方法是“把鸡蛋放在不同篮子里”。"
  },
  {
    "question": "在「集群管理」中，“故障转移 (Failover)”机制的主要作用是什么？",
    "options": [
      "在主节点发生故障时，自动将流量切换到备用节点",
      "在正常运行时，将请求均匀分配给所有节点",
      "通过减少集群中的节点数量来降低成本",
      "定期将主节点的数据备份到备用节点"
    ],
    "correctAnswerIndex": 0,
    "explanation": "“故障转移”是为应对故障而设计的。其核心功能是在监控到主节点（或活动节点）失效时，能够自动地、迅速地将服务或流量切换到预先准备好的备用节点上，从而保证服务的连续性。",
    "source": "文档中「4. 集群管理」部分的「策略」",
    "hint": "这个机制的名字“Failover”直译过来就是“失败时接管”，它是在什么情况下被触发的？"
  },
  {
    "question": "文档将“微服务架构”归类为哪种宏观设计策略的应用实例？",
    "options": [
      "负载均衡 (Load Balancing)",
      "冗余设计 (Redundancy Design)",
      "去中心化设计 (Decentralized Design)",
      "备份和恢复 (Backup and Recovery)"
    ],
    "correctAnswerIndex": 2,
    "explanation": "微服务架构通过将庞大的单体应用拆分为一组小而独立的服务，每个服务都可以独立开发、部署和扩展。这种做法避免了核心功能的集中化，符合“去中心化设计”的理念，从而降低了单点故障的风险。",
    "source": "文档中「5. 去中心化设计」部分的「策略」",
    "hint": "这种架构的核心思想是“分而治之”，避免权力或功能过度集中。"
  },
  {
    "question": "除了使用冗余组件外，「设计容错机制」一节还提到了哪种具体的策略来处理网络通信中可能出现的暂时性故障？",
    "options": [
      "增加网络带宽以减少延迟",
      "采用超时和重试机制",
      "将所有请求集中到单一的强大服务器处理",
      "使用更严格的安全加密协议"
    ],
    "correctAnswerIndex": 1,
    "explanation": "当一个服务调用另一个远程服务时，网络可能会暂时中断或对方服务暂时无响应。设置一个“超时”时间可以避免无限等待，而“重试”机制则允许在短暂故障后再次尝试，这是一种简单而有效的处理暂时性故障的容错策略。",
    "source": "文档中「7. 设计容错机制」部分的「策略」",
    "hint": "当你打电话给朋友，对方没接，你通常会挂断（不再无限等待），然后过一会儿再打一次。这个过程对应了哪种技术机制？"
  },
  {
    "question": "综合文档内容，“冗余设计”和“备份与恢复”在应对系统故障时，最根本的区别是什么？",
    "options": [
      "冗余设计主要针对硬件，而备份主要针对软件数据",
      "备份过程是自动的，而冗余切换需要人工干预",
      "冗余设计旨在故障发生时系统能无缝继续运行，而备份用于故障发生后恢复系统",
      "冗余设计成本更高且效果更好，备份成本低但恢复慢"
    ],
    "correctAnswerIndex": 2,
    "explanation": "“冗余设计”（如热备、集群）的核心是高可用性，即当一个组件失效时，冗余的组件能立即接替其工作，保证服务不中断或中断时间极短。而“备份与恢复”是一种灾难恢复策略，它关注的是在系统或数据遭到破坏后，如何从一个历史时间点（备份点）恢复数据和服务，这个过程通常会有一定的停机时间。",
    "source": "综合理解文档中「1. 冗余设计」和「6. 备份和恢复」部分",
    "hint": "一个是为了让系统在出问题时也能撑住（高可用性），另一个是在系统彻底瘫痪后进行重建（灾难恢复）。"
  }
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                '</div>' +
                '</div>';

            let reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }
            quizContentEl.insertAdjacentHTML('beforeend', finalScoreHtml);
            document.getElementById('review-btn').addEventListener('click', reviewQuiz);
        }

        function reviewQuiz() {
            const reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }

            document.querySelector('.quiz-body').style.display = 'block';
            document.getElementById('quiz-footer').style.display = 'flex';
            
            currentQuestionIndex = 0;
            loadQuestion();
            updateNavigationButtons(); // Ensure nav buttons are correctly displayed
        }

        // Event Delegation for options
        optionsListEl.addEventListener('click', (event) => {
            if (event.target && event.target.matches('li.option-item')) {
                // Check if the question has already been answered
                if (userAnswers[currentQuestionIndex] === null) {
                    const selectedIndex = parseInt(event.target.dataset.index, 10);
                    selectOption(selectedIndex);
                }
            }
        });

        prevBtn.addEventListener('click', goToPreviousQuestion);
        nextBtn.addEventListener('click', goToNextQuestion);
        hintBtn.addEventListener('click', showHint);
        
        // 初始加载
        loadQuestion();
      </script>
    </body>
    </html>
  